The creation of a cost-effective reliable digital hard proof has eluded the graphic arts industry to date. There are stringent requirements for color consistency and repeatability. These requirements have, in the past, caused digital proofing systems to be expensive, typically in the range of $100,000, and difficult to maintain and keep in calibration. Some systems even require climate and humidity controlled environments to operate properly.
There are three main elements that go into making a digital proof: Data, Materials (ink or toner and paper) and a Marking Engine. If the materials and marking engine are good, then a valid proof should be able to be produced provided that the data is properly prepared, and the marking engine is calibrated. Even if a good quality proof is produced, there is still the problem of getting the printer or publisher to accept it.
Over the past few years the cost of inkjet and laser printers has declined, and the quality of their output has improved dramatically. These printers are starting to be used to proof material for reproduction on printing presses. However, due to inconsistencies in output, printers and publishers are reluctant to accept these low cost proofs as a valid representation of a digital file to be printed.
The present invention addresses this need by providing a two-part color bar process, one pre-printed (preprinted) and one printed with the proof content, thus allowing inexpensive inkjet or laser printers to produce color proofs that can be demonstrated as being valid. The process provides a quick check to ensure that the color being output by a marking engine on specially prepared proofing material is within acceptable calibration limits.
A hard proof is created that can be visually inspected to determine if it meets industry standards. The proof has a content image portion and color bar image data. To create the hard proof, a sheet of proofing paper is provided that has one or more known good first color bars pre-printed thereon, but no content image portion printed thereon. The content image portion of the proof and one or more second color bars are then printed on the sheet of proofing paper. The one or more second color bars are printed on the proofing paper in a pre-defined relationship to the one or more first color bars so as to allow for visual inspection directly on the proofing paper using only the color bar image data of the first and second color bars, and without using any external color reference materials. A visually discernable color match indicates that a proof which meets industry standards has been made and a visually discernable color mismatch indicates that a proof which meets industry standards has not been made.